Defrost
Air cooling evaporators working below 0C will accumulate Morozov, that must be removed periodically, as this will prevent heat transfer. Where the air is always at +4C or above, it will be enough to stop the refrigerant time and allow frost to melt off (as in the auto-defrost domestic refrigerator). This method can be used to coldrooms, packaged air conditioner and others when the term of service may be interrupted.
For lower temperatures, heat must be applied to melt frost within a reasonable time and make sure it flows. The methods used are as follows:
- Electric resistance heaters. Elements inside the coil or directly below it.
- Hot gas. Pipes from the compressor discharge feeds superheated gas to the coil. The compressor should be still working on another evaporator hot gases. Heat accumulation capsules can be integrated into the circuit to provide a limited reserve of heat for a small installation.
- Reverse cycle. The direction of refrigerant flow in the reverse order to act as the evaporator in the condenser. Heat the battery or the other evaporator is needed as a source of heat.
In each of these cases, measures should be taken to remove cold cooling-ant from the coil while defrosting is in progress. Trays and drainage pipes, which may require additional heating.
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Evaporators